1. Field of the Invention
The present invention relates to a drafting instrument, and more particularly to a drafting instrument capable of drafting various sizes of geometrical figures including squares, rectangles and triangles or the like.
2. Brief Description of the Prior Art
Conventionally, there have been various forms of frame-shaped rules (hereinafter, referred to "frame rules") each provided with an opening of a definite size for drafting a square, triangle or the like geometrical figures.
However, in the case of using the conventional frame rules, it is impossible to draft a figure having a desired dimension.
For example, in drafting a rectangular figure, which is most frequently drafted, normally a set of triangular rules are employed, where a necessary dimension of the figure is in advance determined through measurement, and thereafter the actual drawing of the figure is performed based on the obtained dimension. Accordingly, the process is complicated, time consuming and troublesome.
A right-angled isosceles triangle, by using a frame rule having a square opening, can be drafted utilizing adjacent sides of the rule. However, the commercially sold frame rule having no scale of dimension, there is still a disadvantage that, for drawing two sides having an equal length, each of the sides must be separately measured to draft the figure.
Further, although a conventional drafting machine in combination with a right-angled triangular rule may be also used, it is impossible to accurately draft a square or a regular triangle owing to increased number of processes or irregularity of measured positions.
The present invention is made to overcome the disadvantages of the prior art devices.